Jie Li, Suhang Guo, Hua Yu, Xiaobo Hong, Jing Nie, Hua Sun
BACKGROUND: Hashimoto's thyroiditis (HT) is a prevalent autoimmune thyroid disease (AITD) closely linked to genetic predisposition and environmental factors. Gut microbiota dysbiosis has recently been implicated as a critical contributor to AITDs' pathogenesis. Our study aims to systematically investigate the dynamic alterations in gut microbial communities under varying thyroid functional statuses and elucidate their underlying mechanisms. METHODS: 67 HT patients with varying thyroid functional statuses and 23 healthy controls were enrolled. Fecal 16 S rDNA sequencing and analyses (alpha diversity, LEfSe, correlation, functional pathways) assessed microbiota-thyroid function links. RESULTS: HT patients with hypo/hyperthyroidism had lower gut microbiota richness than euthyroid patients (more reduced in hyperthyroidism). The hyperthyroid group exhibited enrichment of Fusobacterium, the hypothyroid group was dominated by Clostridium sensu stricto_1, and the euthyroid group showed a predominance of short-chain fatty acid (SCFA)-producing bacteria (e.g., Lactobacillus). Clostridium sensu stricto_1 positively correlated with TPO-Ab levels but negatively correlated with FT3.Pro-inflammatory genera(e.g., Escherichia-Shigella, Streptococcus) demonstrated negative correlations with FT3.Functional prediction analysis revealed potential associations with L-tyrosine degradation in the hyperthyroid group, reduced proportions of bile acid metabolism pathways in the hypothyroid group, and enriched proportions of fatty acid metabolism pathways in the euthyroid group. CONCLUSIONS: This study revealed that gut microbiota dysbiosis is closely associated with thyroid functional statuses in HT. Specific bacterial genera, such as Clostridium sensu stricto_1 and Fusobacterium, may contribute to immune regulation and disease progression. The dynamic alterations in gut microbial profiles provide potential biomarkers for precision diagnosis and treatment of HT.